Droplet impact regime maps

Fig. 3.2. Typical droplet-droplet collision outcome map with four regimes [88] Bouncing (Bo), Coalescence (Co), Stretching Separation (Ss), and Reflexive Separation (Rs). X denotes the impact factor, and TVe is the Weber number.

Figure 18.49 shows two cases of off-centre collision with different impact numbers B). In the first case, the particle completely penetrates into the droplet in the second case, the particle partially penetrates into the droplet, and then is ejected by droplet surface. It can be fotmd that the penetration process for both cases is characterized by the particle rotation. In the case of partial penetration, if the particle spins counterclockwise to penetrate the droplet, it will be ejected from the liquid surface with a clockwise rotation. Unlike in a collision system of two equal-sized droplets [47], a particle of small inertia imposes negligible influence on the motion state of a large droplet. Figure 18.50 (left) shows the regime map of... 

If the fluid dynamic conditions of a droplet are within the spreading regime, i.e., below the threshold curve in the We-Oh map, liquid splashing and ejection from the impact surface can be eliminated. The corresponding threshold velocity can be written as ... 

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